<template>
  <div class="s-canvas">
    <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
  </div>
</template>
<script>
  export default{
    name: 'SIdentify',
    props: {
      identifyCode: { //默认注册码
        type: String,
        default: 'xgw7'
      },
      fontSizeMin: { // 字体最小值
        type: Number,
        default: 25
      },
      fontSizeMax: { // 字体最大值
        type: Number,
        default: 35
      },
      backgroundColorMin: { // 验证码图片背景色最小值
        type: Number,
        default: 200
      },
      backgroundColorMax: {  // 验证码图片背景色最大值
        type: Number,
        default: 220
      },
      dotColorMin: { // 背景干扰点最小值
        type: Number,
        default: 60
      },
      dotColorMax: { // 背景干扰点最大值
        type: Number,
        default: 120
      },
      contentWidth: { //容器宽度
        type: Number,
        default: 100
      },
      contentHeight: { //容器高度
        type: Number,
        default: 36
      }
    },
    methods: {
      // 生成一个随机数
      randomNum (min, max) {
        return Math.floor(Math.random() * (max - min) + min)
      },
      // 生成一个随机的颜色
      randomColor (min, max) {
        let r = this.randomNum(min, max);
        let g = this.randomNum(min, max);
        let b = this.randomNum(min, max);
        return 'rgb(' + r + ',' + g + ',' + b + ')'
      },
      drawPic () {
        let canvas = document.getElementById('s-canvas');
        let ctx = canvas.getContext('2d');
        ctx.textBaseline = 'bottom';
        // 绘制背景
        // ctx.fillStyle = this.randomColor(this.backgroundColorMin, this.backgroundColorMax);
        ctx.fillStyle = '#e685aa';
        ctx.fillRect(1, 1, this.contentWidth, this.contentHeight);
        // 绘制文字
        for (let i = 0; i < this.identifyCode.length; i++) {
          this.drawText(ctx, this.identifyCode[i], i)
        }
        this.drawLine(ctx);
        this.drawDot(ctx)
      },
      drawText (ctx, txt, i) {
        // ctx.fillStyle = this.randomColor(50, 160); // 随机生成字体颜色
        ctx.fillStyle = '#fff'; // 随机生成字体颜色
        ctx.font = this.randomNum(this.fontSizeMin, this.fontSizeMax) + 'px SimHei';  // 随机生成字体大小
        let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1));
        let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5);
        var deg = this.randomNum(-30, 30);
        // 修改坐标原点和旋转角度
        ctx.translate(x, y);
        ctx.rotate(deg * Math.PI / 180);
        ctx.fillText(txt, 0, 0);
        // 恢复坐标原点和旋转角度
        ctx.rotate(-deg * Math.PI / 180);
        ctx.translate(-x, -y)
      },
      drawLine (ctx) {
        // 绘制干扰线
        for (let i = 0; i < 4; i++) {
          ctx.strokeStyle = this.randomColor(100, 200);
          ctx.beginPath();
          ctx.moveTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight));
          ctx.lineTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight));
          ctx.stroke()
        }
      },
      drawDot (ctx) {
        // 绘制干扰点
        for (let i = 0; i < 30; i++) {
          ctx.fillStyle = this.randomColor(0, 255);
          ctx.beginPath();
          ctx.arc(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight), 1, 0, 2 * Math.PI);
          ctx.fill()
        }
      }
    },
    watch: {
      identifyCode () {
        this.drawPic()
      }
    },
    mounted () {
      this.drawPic()
    }
  }
</script>
<style scoped>
  .s-canvas {
    padding: 2px;
  }
</style>
